A device for supplying energy by means of a first DC voltage source e.g. in the form of a DC voltage bus, a drive system comprising several electric motors is connected to said DC voltage bus. The electric motors are comprised e.g. in a number of yarn feeding devices co-acting with a weft insertion system in a shuttleless weaving machine for producing a woven fabric having a multi-colour pattern. The electric motors operate with energy consumption function phases (start and acceleration) and with energy generating function phases (deceleration or braking). The first DC voltage source is associated with at least one second DC voltage source via a variable voltage converter. During operation of the electric motors DC voltage and/or current parameters are detected and used to control the voltage converter to produce an energy flow from the first to the second DC voltage sources during an energy generation function phase, or from the second to the first DC voltages sources during an energy consumption function phase. By said energy flows an evening-out of the voltage variations at the first DC voltage source is achieved. The second DC voltage source comprises capacitors defining an active energy buffer.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An energy supplying device for a group of electric motors alternately operating with energy consumption function phases represented by motor start and motor acceleration function phases and energy generation function phases represented by motor stop or motor deceleration function phases, including a common DC-voltage bus which is connected to the electric motors and via a bi-directional variable voltage converter to at least one active DC-voltage energy storing buffer having at least one capacitor, a voltage converter control unit inserted between the DC-voltage bus and the DC-voltage energy storing buffer for selectively controlling respective energy flows between the DC-voltage bus and the DC-voltage energy storing buffer to either transmit energy from the DC-voltage energy storing buffer into the DC-voltage bus during an energy consumption function phase or transmit energy from the DC-voltage bus to the DC-voltage energy storing buffer during an energy generation function phase of at least one of the electric motors, respectively, wherein all said electric motors are connected in parallel via separate motor controls directly to the DC-voltage bus, wherein the DC-voltage bus is connected via a rectifying function component to a DC-voltage supply unit for supplying DC-voltage via the DC-voltage bus to each of the electric motors at least in the energy consumption function phases, and wherein the voltage converter control unit is arranged for detecting varying DC-voltage and/or current parameters at the DC-voltage bus and at the DC-voltage energy storing buffer, respectively, and to control the voltage converter to direct a respective voltage energy flow into the DC-voltage bus or into the DC-voltage energy storing buffer in order to even out voltage variations in the DC-voltage bus between set predetermined voltage variation limits by determining the direction and/or amount of the respective voltage energy flow in dependence from the detected voltage and/or current parameters the predetermined voltage variation limits of the DC-voltage bus defining a significantly narrower range than a range of voltage variations allowed at the DC-voltage energy storing buffer.
2. The device as in claim 1 , wherein the control unit is connected to a first control system controlling the electric motors of the motor group, or a second control system communicating with the first control system.
3. The device as in claim 1 , wherein the DC-voltage bus is connected with two or more of said DC-voltage energy storing buffers via a corresponding said variable voltage converter for each said DC-voltage energy storing buffer.
4. The device as in claim 1 , wherein the DC-voltage energy storing buffer is controlled by the control unit to operate with a predetermined operation energy charge level lower than a possible maximum energy charge level.
5. The device as in claim 4 , wherein the DC-voltage energy storing buffer is chargeable from the exterior to the predetermined operation energy charge level.
6. The device as in claim 1 , wherein the limits for the DC-voltage bus voltage variations define a range of about 10% of nominal DC-voltage of the DC-voltage bus as provided by the rectifying function component.
7. The device as in claim 1 , wherein the range of voltage variations of the DC-voltage energy storing buffer is between 50 V and 300 V.
8. The device as in claim 1 , wherein the electric motors are high efficiency permanent magnet motors.
9. The device as in claim 1 , wherein the electric motors are provided in yarn feeders of a yarn feeding system, or in a weaving machine, or in one or several industrial robots.
10. The device as in claim 1 , wherein the variable voltage converter comprises at least one inductance connected via two effect transistors to the DC-voltage bus, wherein control inputs of both said effect transistors are connected to the converter control unit for selectively directing a respective DC-voltage energy flow into the DC-voltage bus or into the DC-voltage energy storing buffer, and wherein the converter control unit is connected via a parameter conductor to the DC-voltage bus and via a parameter conductor to a DC-voltage energy storing buffer conductor extending between the inductance and the at least one capacitor, and wherein the capacitor and the effect transistors are connected to ground, and wherein a filter capacitor is provided parallel to both said effect transistors between the DC-voltage bus and ground.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
August 18, 2003
November 9, 2004
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